A book containing all of the buy and sell orders for a specific security that are placed by the public. The public book is kept by an order book official or other market specialists.
Taobiz explains Public Book
The public book is considered closed and is only accessible to the order book official or specialist. The book's keeper is the only person who knows the details of the public orders, such as what price or quantity has been entered. However, market makers are allowed access to the highest bid and lowest offer to facilitate trading.